The overall objective of this project is a biosystematic study of the mosquito genus Toxorhynchites of the Oriental Region. The final publication would include complete descriptions of all known stages, illustrations of larvae, pupae and portions of the adult, distribution, bionomics of all species and keys to all stages. We have incorporated the best aspects of the techniques of cladistics, intuitive and numerical taxonomy applied to a broad range of character sets, including morphological, biological, geographical and ecological characters. Six species groups have been defined and will be revised using conventional taxonomic methods. The numerical taxonomic study involved the processing and analysis of morphometric data using multivariate procedures which included character and standardization, computation of similarity co-efficients, cluster analysis and ordination by principal component analysis and multidimensional scaling. The continuing and increasing interest in the use of Toxorhynchites species as potential biological control agents of pest or vector mosquitoes and their use as laboratory animals for arbovirus studies adds to the need for sound systematic studies. The goal of our project, a biosystematic revision of the Toxorhynchites of the Oriental Region, will provide the necessary taxonomic clarification and stability desired by researchers using these Toxorhynchites for public health related investigations.